Brush



Aug. 11, 1931.

E. A. WILLIFORD BRUSH Filed May 21, 1928 Patented Aug. 11, 1931 1,818,515

umrsn srarns series EDWARD A. WILLIFORD, OF LAKEVOOD, OHIO, ASSIGNOR TO NATIONAL CARBON GO INC., A CORPORATION OF NEW YORK BRUSH Application filed May 21, 1928. Serial No. $9,589

My invention relates to means for constood by referring to the drawings, constinecting electrical conductors to brush memtubing a part thereof, in which,

hers. Figure 1 is a side elevational view of a The carbon and ra )hite brushes ordinarbrush member havin a cabled conductor D .i 2:: 5 ily used in connection wlth rotatlng parts connected thereto. 55

of electrical machines are composed of a Figure 2 is a cross sectional View of the comparatively fragile and friable material brush taken along the line II-II of as compared with the metal conductors or Figure 1.

leads to which the brushes are attached. In Figure 3 is a cross-sectional view of a order to form a satisfactory conducting path brush similar to Figure 2 illustrating a 0 between such brushes and the metal conmodification of my invention; and ductors, a high pressure is necessary. This Figure 4 is a cross-sectional View of a pressure is sufficient to cause a stretching brush similar to Figure 2 illustrating anof the metal parts of the clamping devices other modification of my invention.

and a slight flowing of the clamped-on metal Referring to Figures 1 and 2 a brush 1 is of the conductor. These changes require a provided with a countersunk bore through re-adjustment of the metal or of the strands which the bolt 2 is passed. The walls of the of the conductor in order to maintain a good countersunk portionsat the ends of the bore conducting path. The brushes are subjected are parallel to the axis of the bore and pro- 20 to considerable variations in temperature vide spaces in which the conducting mem- 7 which cause an excessive pressure on the conbers are assembled. The countersunk porductor eyelets at certain times and an intions are preferably of sufiicient depth to suflicient pressure at other times. The vibrapermit the ends of the bolt to terminate just tion to which the brushes are subjected in below the surface of the brush and a chanservice also causes the friable brush mateneled opening 3 is preferably provided in rial in contact with the conductor eyelets to the brush material so that the cabled leads wear away. These things result in defec- 4 can be conveniently introduced into the tive electrically conductive paths between the countersunk portions. Eyelets 5 which are brush and the connector and excessive heatformed in the leads 4 are placed in the coun- I 30 ing and destruction of the brushes result. tersunk bores next to the brush and flat Heretofore the conductors have been washers 6 are mounted on the eyelets. The fastened to the brushes with bolts or rivets Washers maybe made of metal or of anv and no provision has been made to compener d for m t ial so tha t y Win sate for the changes in volume of the, cone na 52 3 e y are depressed and nected parts. Resilient connections have they made to Q Walls of also been proposed but there has been no the bores so that y will 3Q 3 Plstons n means in Such connecting members to confine the conductor material in the bores. vide for a sufficient re-adjustment of the h? ,2 gi pnsseddthgough the brush i 40 parts and a sufficient and constant high pres- B37616 1 f; 3 g l g gt sure to prevent faulty conduction and eX- 161 are 16 C 6 EM on the other end they are held by curved re- Cesslve heatlng at the Palms of Contact of silient Washers 8 and 9 and a nut 10. the brush and conductor.

The resilient washers S and 9 which are I have made a device which provldes a preferablv Cupshaped dished are I 45 Sufficlent Pressure on the brush to glve a iounted on the bolt 2 with their concave good electrical contact and which provides Surfaces f i h th g th t th compensating means to counteract th tact between the washers 8 and 6 will be a pansion, contraction, wear and flow of the small circular area around the bolt 2 near materials of the contact members. the surface of the bolt. For the purpose of My invention will be more fully underillustrating the invention the curvature of ring down a nut 10 on the washer 17.

this modification, there is a resilient comthe washers 8 and 9 has been exaggerated but in practice the nut is screwed down so that the surfaces of the washers are more nearly parallel. The nut 10 is screwed down on the washer 9 with sufficient pressure to form a good contact between the brush material and the cabled conductor eyelets at the ends of the bolt. One end of the bolt may be upset to prevent the bolt from unscrewing.

When the washers 8 and 9 are compressed, a pivotal contact member is formed between the washers and the members bearing thereon. There tends to be a concentration of stresses in the area of the washers 6 near the surfaces of the bolt 2 and in a similar area in the nut. The stresses in the nut are transmitted to the bolt and to the opposite end thereof whereby contact between the brush and the eyelet underneath the bolt head is maintained. The concentration of stresses in the washer 6 tends to compress the central portion of the washer and to dis tribute the stresses in the eyelet material from a mural peripheral area near the bolt. The washers 6 operate as pistons in the countersunk portions of the bore and confine the deformed material of the conductor eyelet within the bore. This action is effective in compressing the eyelet material into close contact with the brush and a perfect conducting path is thereby formed between the conductor and the brush. A change of volume of the eyelet material which makes necessary a re-adjustment of the bolt 2 and washers 6 is effected by the resilient washers which provide a pivotal connection between the bolt and the confined eyelet material and a continuous constant application of the necessary pressure to bring about the re-adjustment. Thus an effective redistribution of stresses is facilitated by this arrangement and a perfect conducting path is maintained.

Although the modification shown in Figures l and 2 is preferred for most purposes, I may employ the modifications shown in Figures 3 and 4. In Figure 3, the curved washers 15 and 16 are mounted on opposite ends of the bolt with their convex surfaces contacting with the washers 6. The concave surface of the'washers face outwardly. The washer 15 bears against the bolt head 7 and the washer 16 bears against a flat washer 17. The structure is assembled by screwpensating element directly connected with each end of the bolt. The oppositely disposed washers compensate for the changes in volume of the elements of the connector and they exert a wedging action on the material of the eyelets 5 in the countersunk bore through the washers 6.

I have found that the pressure need not necessarily be concentrated in the flat wash ers 6 in their central areas. It may be a plied to an outer area of the washers 6. 11 Figure 4, I have shown two washers 18 opposed to each other on the ends of the bolt. The washers 18 are mounted on the washers 6 so that the area of concentrated stresses is in an area of the washers 6 near their margins and the parts are fastened together by forming rivet heads 19 at the ends of the bolt. This arrangement likewise provides a pivotal connection between the connector and the washer 6 and means for compen sating for the changes in the volume of the materials. The wedging of the material of the eyelets 5 is also provided for but in this modification the wedging force is applied at the outer periphery of the washer and tends to force the material toward the central bolt.

Still other modifications of my device may be made without departing from the spirit of my invention. The double cup washer shown in Figure 1 may be used on both ends of the bolt instead of the single washers shown in Figures 3 and 4, tubular rivets may be used instead of solid rivets appropriately shaped springs may be used instead of the cupped washers and other combinations which have not been specifically described may be used. Therefore it is to be under stood that I do not wish to limit my invention except by the prior art and by the invention as defined in the annexed claims.

I claim as my invention:

1. The combination with a brush having an elongated bore therethrough and an enlarged portion at the end of the bore having walls parallel to the bore, of means for connecting a conductor which comprises a bolt member in the bore, a conductor member around the bolt in the enlarged portion of the bore, a perforated flat member adapted to confine the conductor material in said en= larged portion of the bore and a cup-shaped spring element having a circular bearing surface on a portion only of the contacting surface of the washer whereby the washer tends to be deformed and to wedge the confined conductor material when the spring element is compressed.

2. The combination with a brush having a transverse bore therethrough and an enlarged depression at the ends having walls parallel to the axis of the bore, of means for connecting a conductor which comprises a bolt member in the bore, a conductor member mounted thereon in said depression, a washer member adapted to operate as a piston in the depression and to compress the material of the conductor against the walls of the depression, a cup-shaped spring member having a circular bearing surface on a portion only of the contacting surface of the washer, and means cooperating with said bolt to compress said cup-shaped members whereby a resilient pivotal connection is formed between said bolt and conductor members.

3. The combination with a brush having a transverse bore and an enlarged depression at the ends having walls parallel to the axis of the bore, of means for connecting a conductor which comprises a bolt having a head on one end and threaded means on the other end, conductor members mounted on the bolt in the depressions, washers on said members adapted to operate as pistons in the depressions and to compress the material of the conductor members against the walls of the depressions, a pair of cup-shaped spring members having their concave surfaces facing each other mounted between said threaded means and one of said washers whereby a compensating pivotal connection is formed between said bolt and conductor members.

4. In a current-carrying brush having a hole therethrough, a lead, means for attaching said lead to said brush comprising a,

clamping bolt within said hole, said lead having a terminal engaging one end of said bolt and disposed adjacent to the side of said brush, a clamping nut for fixing said terminal against the side of the brush and resilient means carried by the bolt for preventing stretching thereof by reason of thermal expansion of the brush, said resilient means being so designed as to provide resiliency substantially equal to the elastic tensional limit of said clamping bolt.

5. In a current-carrying brush having a hole therethrough, a lead, means for attaching said lead to said brush comprising a clamping bolt within said hole, said lead having a terminal engaging said bolt and disposed adjacent to the side of said brush, a clamping nut for fixing said terminal against the side of the brush and a cupshaped spring washer carried by the bolt and capable of withstanding pressure substantially equal to theelastic limit of said bolt, said washer being capable of sufficient deflection to offset any tendency of said bolt to stretch.

6. In a current-carrying brush having a hole therethrough, a lead, means for attaching said lead to said brush comprising a clamping bolt within said hole, said lead having a terminal engaging one end of said bolt and disposed adjacent to the side of said brush, a clamping nut for fixing said terminal against the side of the brush and a spring washer carried by the bolt for preventing stretching thereof by reason of thermal expansion of the brush.

7. In a current-carrying brush having a hole therethrough, a lead, means for attaching said lead to said brush comprising a clamping bolt within said hole, said lead having a terminal engaging one end of said bolt and disposed adjacent to the side of In testimony whereof, I afiix my signature,

EDWARD A. WILLIFORD. 

